Sweetwater: an underrated crude glycerol for sustainable lipid production in non-conventional yeasts

Sweetwater, a methanol-free by-product of the fat splitting process, is an emerging alternative feedstock for microbial utilization of crude glycerol. Yeasts are promising candidates in this context due to their versatility in delivering a wide range of value-added products including lipids. To enhance sweetwater utilization, we investigated the growth and lipid production of 21 oleaginous yeast strains in sweetwater and found that nutrient limitation and the unique carbon composition of sweetwater boosted significant lipid accumulation in several strains, in particular Rhodosporidium toruloides NRRL Y-6987. To decipher the underlying mechanism, the transcriptomic changes of R. toluroides NRRL Y-6987 were further analyzed, indicating potential sugars and oligopeptides in sweetwater supporting growth and lipid accumulation as well as exogenous fatty acid uptake leading to the enhanced lipid accumulation. Our comparative study successfully demonstrated sweetwater as a cost-effective feedstock and suggested potential sweetwater type and strain engineering targets for increasing microbial lipid production. ![Figure][1] ### Competing Interest Statement The authors have declared no competing interest. [1]: pending:yes